Customer found that they had IEE3603D in SYS1.PARMLIB(IEAFIXxx) and it had for MIM in the comment.
Does MIM has requirements to define IEE3603D in IEAFIXxx ?
Release: MIMALM00200-12.1-MIM-Resource Sharing-for z/OS-Plus MSU
MIM has no requirements to define IBM module, IEE3603D, on IEAFIXxx. it may be a workaround on some problem in old MIM release.